Being excellent in its properties such as strength, ductility and transparency, polyvinyl chloride fiber has been used frequently as a fiber for insect net and artificial hair; for example, a method has been disclosed for the production of a polyvinyl chloride fiber comprising a composition having a vinyl chloride resin and a chlorinated vinyl chloride resin (e.g., JP-B-60-18323).
In the polyvinyl chloride fiber of this means, one component is dispersed in the other component as an islands component inside the fiber, and the fiber is crimped by heating.
However, according to the polyvinyl chloride fiber of the aforementioned means, when a heat of 100° C. or more is applied to the fiber for carrying out its secondary processing, its heat shrinkage progresses more than the necessity so that the processing characteristics become poor.
In this connection, a method in which heat shrinkage of a resin composition itself is reduced by increasing formulating amount of a chlorinated vinyl chloride resin in the composition can be considered for the purpose of adjusting crimpness of the fiber, but since the vinyl chloride resin and chlorinated vinyl chloride resin are originally poor in compatibility, simple increase in the blending amount of chlorinated vinyl chloride resin causes phase separation when melt spinning of the fiber is carried out, and the spinning performance therefore becomes poor which is not desirable.
Accordingly, for the purpose of improving compatibility of the vinyl chloride resin with the chlorinated vinyl chloride resin, a method in which an ethylene-vinyl acetate/vinyl chloride graft polymer resin prepared by graft-polymerizing vinyl chloride to an ethylene-vinyl acetate copolymer is added thereto has been disclosed (e.g., JP-A-10-102317).